Low Frequency Amplifier Inverter Using SiC Semiconductors
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Solution Overview
Problem
Existing low frequency sonobuoy amplifier designs struggle to simultaneously achieve high drive voltage, high power density, high efficiency, and wide bandwidth operation due to the inefficiencies and size constraints of low frequency boost transformers, particularly at the 600 Hz to 1100 Hz frequency band.
Innovation Solution
A 2-stage design incorporating a multi-level DC-AC inverter topology with 1.7 kV silicon carbide semiconductors and a phase shifted full bridge input DC-DC converter, eliminating the need for a low frequency boost transformer, which enables high drive voltage, high power density, and high efficiency while maintaining a compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a low frequency boost transformer is used to achieve high drive voltage, then the drive voltage requirement is met, but the transformer becomes large in size and/or inefficient
Solution Approach 1:
The patent replaces the mechanical low frequency boost transformer with an electronic solution consisting of a high frequency transformer operating with pulse width modulation (PWM) and a low pass filter. This substitution eliminates the need for a large, inefficient low frequency transformer while achieving the same high drive voltage output through electronic switching and filtering techniques
Solution Approach 2:
The patent changes the operating frequency parameter from low frequency to high frequency for the transformer operation. By operating the transformer at high frequency with PWM control and then filtering the output, the system achieves high drive voltage with a much smaller transformer size, directly resolving the size-voltage contradiction
2Stress or pressure
If a low frequency boost transformer is used to achieve high drive voltage, then the voltage requirement is met, but the efficiency decreases creating thermal problems
Solution Approach 1:
The patent replaces the inefficient low frequency transformer with a high frequency PWM-based electronic system. The high frequency operation allows for much lower core losses and copper losses, significantly improving efficiency while still achieving the required high drive voltage through the combination of PWM switching and low pass filter output
Solution Approach 2:
The patent employs periodic pulse width modulation (PWM) switching to control the high frequency transformer. This periodic switching action allows for efficient energy transfer and control, enabling the system to achieve high drive voltage with minimal energy loss and reduced thermal problems compared to continuous low frequency transformer operation
3Stress or pressure
If a low frequency boost transformer is used to achieve high drive voltage, then the voltage requirement is met, but the available space for other components is reduced
Solution Approach 1:
The patent replaces the bulky low frequency transformer with a compact high frequency PWM-based electronic system. This substitution dramatically reduces the space required for the voltage generation subsystem, thereby increasing the available space for additional components such as sonar transducers, hydrophones, battery capacity, or other electronics
4Speed
If the low frequency transformer operates at the extremes of the 600 Hz to 1100 Hz frequency band, then the frequency requirement is met, but the efficiency is reduced
Solution Approach 1:
The patent implements dynamic PWM control that can adapt to different operating frequencies within the 600 Hz to 1100 Hz band. This dynamic control allows the system to maintain high efficiency across the entire frequency range by optimizing the switching parameters and duty cycle, eliminating the efficiency penalties that would occur at frequency extremes with a fixed low frequency transformer design
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves high drive voltage (≥1100 Vrms), high efficiency (≥85%), and wide bandwidth (600 Hz to 1100 Hz) operation, extending sonobuoy operation time and enabling more complex location tracking methods, while reducing thermal issues and space constraints.
Implementation Method 1
The input DC-DC converter boosts the low voltage from an input battery and generates a high voltage multi-level DC bus
Implementation Method 2
The output DC-AC inverter converts the high voltage from the multi-level DC bus to a high voltage AC drive voltage waveform
Data Source
AI summary
A low frequency direct drive amplifier is disclosed which can simultaneously achieve high drive voltages, high power density, high efficiency, and wide bandwidth operation is disclosed. The power circuit structure includes an input DC-DC converter and an output multi-level DC-AC inverter. The input DC-DC converter's circuit topology is commonly referred to as the phase shifted full bridge, which includes input capacitors, a Gallium Nitride (GaN) based full bridge, an isolation transformer, two rectifying diodes, and two series stacked output capacitors. The output DC-AC inverter includes two series stacked input capacitors (same as the input DC-DC converter's output capacitors), four Silicon Carbide (SiC) semiconductors, four Silicon IGBTs, and an output filter. The disclosure's features the combination of the output multi-level DC-AC inverter circuit topology paired with 1.7 kV SiC semiconductors, allowing for a high voltage direct drive design without a low frequency boost transformer.